Method of treating fiber-bearing material



N. K. DAVIS METHOD OF TREATING FIBER BEARING MATERIAL Feb. 19, 1924.

' liar/917602".

Filed Nov. 30. 1921 1629215 Kla zlsn v 62m r-zy Maw-1219i Patented Feb. 19, 1924. 1

UNITED STATES PATENT OFFICE.

NORRIS K. DAVIS, OF SAN FRANCISCO, CALIFORNIA,

METHOD OF TREATING FIBER-BEARING MA TER- IAL.

Application filed November 30, 1921, Serial No. 518,912.

The hereinafter described invention com prises a method for the treatment of ores containing asbestiform serpentine, commonly known as asbestos, for the separation and recovery of the asbestos fiber from its en.- closing rock. However, the invention is not restricted to the treatment of such material, inasmuch as it is adapted for the treatment of fiber bearing ores generally for the separation and recovery of the fiber therefrom. In the treatment of asbestos bearing ores as carried out prior to the present invention, it has been customary to first crush the ore and to then pass the crushed material through screens and dusters for the separation of the fiber from the base or worthless material, after which the separated fiber is subjected to a cleaning action. Thismethod of treatment not only requires the employment of expensive and heavy machinery, but the utilization thereof in the treatment of the fiber bearing ore for the recovery of the asbestos therefrom is such as to materially damage the fiber contained within the ore, and by reason of the injury thus done to the 'fiber in the breaking of the same destroys the length thereof and the value of the recovered fiber is materially lessened for use 1 in the industrial arts;

By the use of the present invention, which dispenses with the" employment of the hitherto employed crushing mechanism, the screening, clusters and cleaning means, I an enabled to make a recovery of the asbestos fiber from its enclosing rock withoutbreaking'down ordestroying the length of the 11berated fiber, thereby producing asbestos fiber able tensile strength and of a length-capable 1 invention,

to be separated and recovered therefrom 1s of being spun into threads for the manufacture therefrom of asbestos cloth. a

In the carrying out of the present method the ore carrying the asbestos fiber first reduced in any suitable manner to proper size for handling, and as such reduced,

.sure, the same @throutgh an outlet or exhaust stack -there ore is fed into what is commonly known as an impact centrifugal mill. Here the reduced ore passes from the center ofthe centrifugal runner of the mill, and discharging outwardly therefrom, isthrown with considerable force upon or against a circular anvil arranged within the inill,jthe impact blow thus given to the reduced ore causing a shatteringthereof and liberation of the asbestos and a separation crushed ore, while of the same from the the clusters of fiber so released striking against the anvil of the mill is, by the impact blow thereof, shattered and reduced more or less into individual fibers, but without, injury to its length and tensile strength. -.The material thus treated or broken down falls to the bottom portion of the mill and'is blown therefrom by the stream of air under pressure and conveyed thereby into a centrifugal separator situateda short distance therefrom and into' which the discharge conduit of the mill is extended. In the separator the clusters of fiber not yetreduced to individual fibers are brokenup and separated. By introducing the broken up ore. material with the sepa-- rated fiber into the centrifugalseparator by an air blast under suflicient conveying presis caused tottravel around the inside of the annular body of the separator and during such course of travel the remaining clusters of fiber in the mixture be-v come, further dividual. fibers, the heavier rock or refuse 'material and sand being thrown centrifugallyoutwardly and falling by gravity to the bottom of the separator for discharge therefrom, whilethe lighter fiberis drawn toward the inside of the rotating mass and withdrawn by suction from within the se arator liaading rom. This pneumatic withdrawal of the separated fiber is accomplished by means of an exhaust fan which forces the'material ninto a settling chamber and therefrom into of substantial uniformity and of consider-' and through a classifier designed to receive the said separated fiber. The dust laden air makes its escape or discharge from the set.-

separated or reduced to intling chamber through a suitably controlled outlet stack, while the heavier particles or separated fiber is forced by the air under pressure from within the settling chamber into and through the, classifier, within which the material settles by specific gravity'i'nto it will be noted that fiber liberated from conveyed into a v centrifugal mill and discharged therefrom and forced through pressure,

a classifier by air under and wh1ch constitutes the sole medium or transfer vehicle employed for properly disintegrating the mass of mineral fibers into individual fibers and freeing the same of the dirt and foreign material contained therein, whereby the separation and recovery of the mineral fiber is accomplished without injury or damage thereto and without breakmg down and destroying the length of the The method may therefore be said to reside inthe utilization ofpneumatio means for primarily breakin up the sized ore to liberate, the fiber there rom, thence transferring the sized ore in its broken down condition to a. centrifugal separator for the dividing of the mineral fiber into individual fibers and removing therefrom foreign material adhering thereto, thence transferring the same through pressure to a settling chamber wherein the dust laden air is removed and the separated mineral fiber permitted to settle and be discharged under air pressure into a classifier and within which classifier the separated mineral fibers settle by gravity.

Any suitable form of mechanism may be employed for the mechanical handling of the material, there being illustrated in the accompanying drawings a longitudinal sectional view in side elevation of a suitable apparatus for the carrying out of the desired work and to which drawing reference should be had. i i 1 In the drawings, the numeral l'is used to designate a bin .or hopper for receivin slzed ore to be treated, which ore is elivered by a worm feed 2 into and centrally of a centrifugal mill 3, the fed material falling centrally .of the runner 4 within said mill and being thrown outwardly against a die-ring or anvil 5 secured within the mill, the impact blow of the material being sufficient to shatter and break up the ore to liberate the mineral blast from the mill 3 forces the broken up material through the conduit 7 into the centrlfugal separator 8, and into which air is admitted from the outside through the adjustable air inlets 9. The material as dehvered within the centrifugal separator is thrown against the inner wall of the separator body 10, which serves to break up the clusters of fiber and reduce the same to individual fibers, the base ,Or'refuse material flowing downwardly by gravity and dischargin from withmthe the disc ar outlet 11.

the medium of the air the fiber therefrom. The air s iplarator through. e air pressure metros within the centrifugal separator, draws the liberated mineral fiber towards the center of the separator, from which it is discharged through the uptake 12' and therefrom through the downwardly extended conduit leg 13' into a settling chamber 14;, the material being withdrawn from the separator and upwardly through the up take 12 and downwardlythrough the con-' duit extension 13 by means of the exhaust fan 15,- which forces the material under pressure into the said lighter particles and dust flowing with the bod of separated fiber discharges from the sett ing hamber through the outlet stack 16, which is controlled by the regulating damper 17 while the heavier material or separated fiber settles downwardly by gravity and is discharged by the pressure of the flowing air through the outlet conduit 18 into the classifier 19, being carried therethrough by the flowing body of air under pressure, and as.

chamber 14:. The

moved through the classifier the separated fiber by gravity settles within the series of receiving bins 20 forming the bottom of the classifier, while the dust laden air flowing throu h the classifieresoapes therefrom through t e outlet Stack 21.' The gradin of the separated fiber as carried or propelle through the classifier takes place by gravity, although some of the dust carried by the flowing stream of air under pressure passing through the classifier may settle and accumulate 1n the last of the series of bins. While I have described a practical efiicient apparatus for the carrying out of the method invention, it will be understood that any suitable form of mechanismmay be employed for this purpose just so long as the medium orv vehicle broken up body of ore throughout the various steps of the process comprises a flowing body of air under pressure, whereby the material under treatment in the various steps of the method is not mechanical grindin or crushing action which breaks the her and destroys the length thereof.

The described ore, cleaning, dusting and class1 fiber separated from the ore by the utilization of a conveying medium consisting of a flowing body of air under pressure is be-- lieved to be new, and it is the. desire and method of millin asbestos and for propelling the 305 subjected to a ying the wish to claimthe same as broadly as the of sufiicient l- 1 by means of the exhauster, coupled with a' proper introduction of considerably more air into the se arator, will draw off the fiber into the discharge pipe of the separator from whence it passes nto the exhauster.

The fiber passing to the exhauster will contain some light sahd, dust, loose fiber and partly disintegrated fiber clusters. The action in the discharge pipe of the se arator and the exhauster is to separate out t sand and dust, disinte remain, and separate e light ate what loose fibers 0 dust still adhering to the same.

Having thus described my invention, what mm the fiber particles I claim as new and desire to secure by Letters Patent of the United States is The' method of treating fiber bearing ores reduced to a proper size for the separation and recover of the fiber therefrom, which resides in s attering the ore by an impact blow of the from, subjecting the released fiber to the action of air under pressure to permit the baser refuse material to settle out by gravity subjecting the separated fiber and lighter particles to air under pressure toremove the dust and light particles therefrom and classifying the fiber according-to length by forcing the same in a horizontal direction by air under pressure and permittingthe dischargedfiber to settle by gravity.

In testimony whereof I have name to this specification.

NORRIS K. DAVIS.

signed my ore to release the fiber there- 

